IDA-101 End of unit 10

Which of the following is the largest electrical load in an air-conditioning or refrigeration system?

• evaporator fan motor

• condenser fan motor

• compressor

• relay coil

Which of the following is the major difference between a relay and a contactor?

• ampacity rating

• number of contacts

• mechanical linkage

• none of the above

What is the major difference between a magnetic starter and a contactor?

• A magnetic starter includes overload protection, while a contactor does not.

• A contactor is used for DC circuits, while a magnetic starter is used for AC circuits.

• A magnetic starter is used for low voltage applications, while a contactor is used for high voltage applications.

• A contactor is more expensive than a magnetic starter.

The purpose of a contactor or relay is to:

• Control a large amount of current with a small control signal

• Measure electrical resistance

• Convert AC to DC

• Store electrical energy

Explain the operation of a contactor and a relay.

• A contactor is used for high power applications, while a relay is used for low power applications.

• When the correct voltage is applied to the relay or contactor coil, the contacts will close.

• Both contactors and relays are used for high power applications.

• Both contactors and relays are used for low power applications.

What are the two types of armatures used in contactors and relays?

• sliding, swinging

• rotating, fixed

• linear, rotary

• pivoting, stationary

What are the three major parts of a contactor or relay?

• coil, contacts, mechanical linkage

• coil, resistor, capacitor

• contacts, diode, transistor

• mechanical linkage, switch, fuse

What is the proper procedure for checking the coil of a contactor or relay?

• Measure the resistance with a multimeter

• Check for non-physical damage

• Ensure the power supply is connected

• none of the above

Contacts are usually made of _____.

• silver or cadmium attached to a copper base

• aluminum or zinc attached to a steel base

• gold or platinum attached to a plastic base

• iron or nickel attached to a wooden base

What are the major reasons for replacing the contacts of a contactor?

• Wear and tear due to frequent operation

• Corrosion from environmental factors

• Electrical arcing damage

• All of the above